With reference to FIG. 1, double-walled cryogenic storage vessels comprise an inner vessel and an outer vessel spaced apart from and surrounding the inner vessel, where the space between the vessels is a thermally insulating space, such as a vacuum space, that reduces heat leak into a cryogen space inside the inner vessel. The inner and outer vessels can have a horizontal configuration where the longitudinal axis (10) extends along the horizontal plane. In vehicular applications the inner and outer vessels are exposed to various loads, such as axial loads, radial loads, and torsional loads as the vessels experience forces acting upon them during acceleration of the vehicle. Axial loads acting on the inner vessel are defined herein to be the loads acting in a direction parallel to the longitudinal axis, which defines the “axial direction”. The radial axis (20) intersects the longitudinal axis at right angles. Radial loads acting on the inner vessel are defined herein to be the loads acting in a direction transverse to the longitudinal axis and parallel with the radial axis, which defines the “radial direction”. Torsional loads acting on the inner vessel are defined herein to be the loads acting in a direction transverse to the longitudinal axis and the radial axis, such as in the direction of axis (30) in FIG. 2, and which result in the inner vessel rotating about the longitudinal axis with respect to the outer vessel.
In the Applicant's co-owned U.S. Pat. Nos. 7,344,045 and 7,775,391, axial, radial and rotational movement of the inner vessel with respect to the outer vessel is constrained, at one end of the cryogenic storage vessel, by piping that extends from the cryogen space to outside the cryogenic storage vessel, and which is attached to support brackets secured to the inner and outer vessels. At the opposite end of the cryogenic storage vessel the inner vessel is constrained in the radial direction with respect to the outer vessel, and is free to move in the axial and rotational directions. The inner vessel is constrained to move in the axial direction at one end of the cryogenic storage vessel only to allow for axial expansion and contraction of the vessels while the cryogenic storage vessel is thermally cycled between ambient temperature and cryogenic temperatures. In one technique of constraining radial but not axial or rotational movement, a non-metallic support extends between two support brackets connected with the inner and outer vessels respectively at one end of the cryogenic storage vessel. In another technique, two straps extend in opposite directions from a collar around a bearing surface of a non-metallic support (secured to the inner vessel) and which are secured to the inner surface of the outer vessel. The collar and bearing surface allows for axial movement of the inner vessel with respect to the outer vessel, while the straps constrain the radial movement of the inner vessel.
One problem with cryogenic storage vessels that constrain only the radial movement of the inner vessel with respect to the outer vessel, at one end, is the stress put on vessel supports at the opposite end due to the unconstrained rotational movement at the one end creating a torsional load between the vessels that can fatigue supports. The state of the art is lacking in techniques for constraining radial and rotational movement between the inner and outer vessels of a double-walled cryogenic storage vessel at one end, while allowing for axial movement at that one end. The present apparatus provides a technique for improving cryogenic storage vessel supports.